Two-wire automatic and manual telephone-exchange trunking system.



E. D. FALES.

TWO WIRE AUTOMATIC AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM. APPLICAHON FILED MAR. Ir. 19:0. ssuswsn NOV. 10,1sx7.

1 ,270,277. Patented J1me 25, 1918.

16 SHEETSSFEET I.

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TWO WIRE AUTOMATIC AND MANUAL T ELEPHGNE EXCHANGE TRUNKING SYSTEM.

APPLICATION mm) MR. 1!, 1910. RENEWED NOV. 10.1912

Patentml June 25, 1918.

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E. D. FALES.

TWO WIRE AUTOMATICVAND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM. APPLICATION FILED MAR. 17, I910. RENEWED NOV. 10,1917.

1,270,277. Patented J une 25, 1918.

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flTTOR/VEY E. DJFALES. TWO WIHE AUTOMATIC AND MANUAL IELEPHONE EXCHANGE TRUNKXNG SYSTEM.

APFLICM'ID N FILED MAR-17.1mm GENEWFD NOV. 0.1917- Patented June 25, 1918.

-"JYYW E. D. FALES.

TWO WlRE AUTOMATIC AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICAHON FILED MAR. H. 29W. RENEWED NOV. 10.1911. 1,270,277.

l'ufvnfed June 25, 1918.-

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TWO WIRE AUTOMATIC AND MANUAL TFLEPHONE EXEHANGE TRUNKING SYSTEM APPLICATION FILED MAB. 17,4910- HiNEWED NOV. 10,191]. 1,270,277.

Patuntd June 25, 1918.

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TWO WIRE AUTOMATIC AND MANUAL YELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICATION HLED MAR.I7,1EUU- RENEWED NGV 01 7- 1,270,27'7 lut'vnrvd Jnnv 25, 1918.

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E. U. FALES TWO WIRE AUTOMATIC AND MANUAL TELEPHONE EXCHANGE IRUNKING SYSTEM APPLICATIGN mu] MAR. 17. 1910. RiNEWED NOV. 10,19l1.

WITNESSES E. D. FALES.

TWO WiHE AUTOMATIC AND MANUAL TELWHONE EXCHANGE TRUNKING SYSTEM.

APPucmoN HLEU MAR. 17. I910. RENEWED NOV 10.1911.

1,270,277. Patented June 25, 1918 6 SHEET5SHEET 9.

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E. D. FALES. TWO WIRE AUTOMATIC AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICATION LED MAR. 31, 19H]. RENEWED NOV. 10.191].

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WITNESSES E. D. FALES. TWO wmi AUTOMAHG AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICATION FILED MAR. 17, I910. RENEWED NOV. H]. 19!].

l'ntonfvd Junv 25, 1918,

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APPLICATION FJLED MAILIL Him RiNEWED NOV, H3. ii'li- 270,277. latvnfml Jun? 25, 1918 I6 SHEETSSHEET 12.

E. D. FALES.

TWO WIRE AUTOMAHC AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICATION FILED MAH.I1.19I0- RENEWED NOV. 10.1917.

Patentvd June 25, 1918..

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W/ T/VESSES E. D FALES. TWO WIRE AUTOMATIC AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICATION FILED MAR. U, 5980. RENEWED NOV- 10.!9".

Patented June 25, 191&

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E. D. FALES.

TWO WIRE AUTOMATIC AND MANUAL TELEPHONE EXCHANGE TRUNKING SYSTEM.

APPLICATION HLED MAR. n. 1910 RENEWED NOV. 10 1911 1,270,277. Patented June 25, 1918.

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TWO WIRE AUTOMATIC AND MANUAL TEtEPHONE EXCHANGE TRUNKING SYSTEM;

APPLICATION HLED MAR. H, 19l0- RENEWED NOV. 10. l9|7. 1,270,277, PatcntedJuno 25, 1918.

16 SHEETSHSHEETJB- w mk wmw mw WITNESSES 1 CM (LL10 UNITED STATES PATENT oEEIcE.

EDWARD D. FAIJES, OF LA GRAIQ'GE, ILLINOIS, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, OF CHICAGO ILLINOIS, A CORPORATION OF ILLINOIS.

TWO-WIRE AUTOMATIC AN D MAIlUAL TELEPHONE-EXCHANGE TRUNKING SYSTEM.

Application filed March 17, 1910, Serial No. 549,816. Renewed November 10, 1817.

To all whom it may concern:

Be it known that I 'Eowano D. FALES, a citizen of the United tates of America, and resident of La Grange, Cook county, Illinois, have invented a certain new and useful Improvement in Two-'Wire Automatic and Manual Telephone-ExchangeTrunking Systoms, of which the following is a specification.

My invention relates to telephone exchange systems in general, but more particularly to automatic or semi-automatic telephone exchange systems of that kind in which automatic switches are used between calling and called subscribers, and in which provision is made for controlling said switches over the two sides of the calling line in series, whereby no operating grounds are necessary at the substations.

Systems of this kind are commonly known as two-wire systems, as distinguished from the other kind of system in which the automatic switches are controlled by grounding first one side of the line and then the other at the calling substation, which latter is commonly known as a three-wire system, the ground or common return between the substations and the exchange being regarded as a third wire, whereas in a twowire system, such as hereinafter described, the automatic switches at the exchange or central station are controlled without grounding the subscribers" lines.

In a two-wire system of this kind it often becomes necessary, especially in large cities where there are several exchanges, to transmit the call, for at least part of the way,

through the medium of manual apparatus, and to provide means whereby an automatic subscriber may call a manual sub scriber, or a manual subscriber may call an automatic subscriber, and it is always do sirable, of course, to make adequate provision, as far as possible, for all of the different kinds of connections that may be found necessary in a complex system of this kind in as convenient and eificient a manner as possible, and in a way that will insure good telephone service for all of the subscribers thereof.

The object of my invention is, therefore, the provision of an improved construction and arrangement whereby certain callin connections heretofore considered impossible in a two-wire system are now made prac- Bpecinoation 01. Letters Patent.

Patented June 25, 1918.

Serial No. 201,397.

ticable, and whereby each subscriber, notwithstanding the many different kinds of apparatus employed, may converse with any other subscriber of the system, as will hereinafter more fully appear.

to theleft of Fig. 1, and with Fig. 3 above Fig. 2, this giving an idea of the whole systom.

Figs. 4 and 5 illustrate diagrammatically the apparatus by means of which a subscriber of the automatic section of exchange may establish connection with another automatic subscriber of the same section, the lines of both of which subscribers terminate directly in the same exchange.

Fig. 6 is a diagram of a repeater involved in said system.

Figs. 7 and 8 are similar illustrations of apparatus used in connection with an automatic district oflice, in which district ofiice the subscribers, in calling each other, do not monopolize any of the trunk lines running to the main otlice while maintaining a talking connection.

Fig. 9 is a similar view of private branch exchange apparatus associated with the automatic section of the combined manual and automatic ofiice.

Fig. 10 is a similar view of a different type of private branch exchange connected with the same automatic section.

Fig. 11 is a similar view of a line equipment of the said system, said equipment adapted for semi-automatic use, together with a rotary connector.

Fig. 12 is a similar illustration of manual and semi-automatic equipment.

Fig. 12" is a modification of a portion of Fig. 12. Y r

Fig. 13 is a similar view of a B-cord equipped with a calling device.

Fig. 1} is a similar view of subscribers.-

equipment and central office apparatus for si naling an operator, and by which the suiscribers are called, used inconnection with the district subscribers. (See Fig. 3).

Figs. 15 and 16 are similar illustrations of automatic apparatus used between A and B operators.

Fig. 17 is a similar view of an automatic switch known as the rotary connector.

Referring more in detail to Fig. 1, if the subscriber A, whose line terminates in the central office containing the automatic tion, wishes to call subscriber A, similarly situated in the system, and whose number it will be assumed is 2320, the subscriber A removes his receiver and thereby operates his line switch C to establish connection with an idle first selector D. The first selector is then operated to raise its shaft two steps and rotate it until connection is made with an idle second selector E in the second thousand. The second selector E is then operated to raise its shaft three steps and rotate it until connection is established with an idle connector F, which connector is finally operated in accordance with the last two digits of the desired number, thus completing the connection if the desired subscriber is idle. Of course, if the subscriber should be busy the 'calling subscriber will be given the busy signal. In that case (and also in the event that connection has been made and the calling subscriber is through), upon hanging up his receiver the calling subscriber releases all of the apparatus brought into use. To explain still more in detail this operation of the subscriber A calling the subscriber #2320, reference ismade to Figs. 4- and 5. It will be understood that the subscriber A, being an automatic subscriber, is provided with a suitable dial such as that shown in the article appearing in the llesfern Electrician of Chicago, Illinois, of January 11, 18 and 25, 1908. As is well known, this dial controls a suitable impulse wheel 2, which in turn, through the medium of a set of teeth 3 provided on its periphery, controls and operates the so-called impulse strings 4 and 5. This telephone is, of course. provided with the usual switch hook and receiver. The switch hook shown adaJted to control and operate the springs ti, and 8. In addition, the telephone has the usual trans mitter 9 and ringer 10 which is connected in series with a condenser 11. The subscriber A is also, as shown, provided with the line switch C to which reference has already been made in connection with Fig. 1, which line switch is of the general character described in the publication hereinabove referred to, and also of the general character of similar apparatus shown and described in British Patent No. 26,301 of 1906. This line switch C together with other line switches of the same group (usually one hundred in number) are rontrolled by the master switch H. The function of this master switch is to always maintain the line switch t. while idle. opposite an idle line which may be used by the sulr scriber A as soon as he removes his receiver without having to wait for a selector. This trunk line, of course, terminates in u selector switch such as the selector switch I), to which reference has already been made. The master switch 11' is also of the general character as that described in the ll'rwfrv'n, Electric/Tun and the British patent hereinabove referred to. Having decided to call the subscriber #2320, the subscriber removes his receiver 12, thereby permitting the switch hook 13 to rise. which in turn permits the springs 13 and 7 to separate. thereby disconnecting the ringer 10 from the circuit, the spring 7 finally engaging the spring 8, thus closing the two sides of the lines 14 and 15 (known, res1. ectively, as the positive and negative sides) through the transmitter l) and the impulse springs 4 and 5 at the telephone. The closure of this cir cuit. causes a flow of current through the line winding 16 of the line switch The path of the current may be traced from ground (11' through the springs 17 and 18 of the line switch to the positive conductor 14, thence to the springs 7 and 8 at the telephone and through the impulse springs 4 and 5, receiver 12, transmitter 9, negative conductor 15, springs 19 and 20 and the winding 16 to the battery lead 21, thence through battery B to ground G. This flow of current causes the line winding 16 to attract the armature of the line switch (7, with the result that the spring 23 is pressed onto the spring 17, whereby an energizing circuit is closed through the pull-in winding 24 and through the auxiliary winding 25, thence through conductor 26, contact 27 and armature to the battcry lead 21, thence through battery B to ground I. The :|ll-in winding 24 being thus energized attracts the plunger armature 29. which then causes the plunger to press the springs 30 and 31. springs 32 and 33, springs 34 and 155 and the springs 36 and 37 into contact. At the same time the winding 24 pulls the MH'nllPtl bridgc-cut-oli' armature 38 down, which in turn acts upon the springs 18 and 1.) to separate them from the springs 17 and 20, respectively, carrying the spring 19 into engagement with the spring 41. It will be seen that this action of the cut-off armature 3R disconnects the line winding 16 from the line. in order to insure that the line armature 22 shall not fall lw'k too quickly, the auxiliary winding 25 is provided, which winding is shunted or short-circuiled by the closure of contact between the springs 42 and 43 when the V is closed onto the conductor such armature 29 reaches its operated position. At this point the armature 22 falls back and the circuit is broken through the pull-in winding 24. In the meantime, however. a holding circuit is established through the bridge-cutoff winding 44 for preventing the armature 29 from falling back until the connection is released. The act of the plunger, which is attached to the plunger armature 29, of pressing the springs 34 and 35 into contact, causes the master switch H to operate, starting it on its selection of the next idle trunk to have the same in readiness for a call. This operation of the master switch is as follows: The closure of the said springs 34 and 35 puts a positive P01011- tial' on the bank contact 45 of the master switch bank a from ground G". This contact 45 corresponds to the trunk line which terminates in the switch D, there being one nk contact for every trunk line/associated with the master switch H. Assuming that the first selector D was idle at the time that the subscriber A removed his receiver, and that the master switch H was holding the line switch C in readiness to connect with the Switch D; then the master switch wiper 46 is in the position indicated in Fig. 4 at the instant that the line switch C operates, and, therefore, the guard ing potential established at the bank contact 45 by the said bank springs 34 and 35 causes a flow of current to pass through the master switch relay 47 through the said master switch wiper 46. The relay 47 upon energizing closes an energizing circuit for the relay 48, which in turn performs the following functionsz First, it disconnects the main battery from the conductor 26, and from all such conductors, thereby rendering all line switches C of the group inoperative for starting a call. Second, the spring 49 26, whereby any subscriber of the group may receive the busy signal and hang up his receiver should he attempt to make a call while the master switch H is in operation. Last, an energizing circuit is closed through the operating magnet 50. Thisenergizing circuit includes the interrupter springs 51. It will be seen that an auxiliary wheel 52 is provided on the same shaft with the gear wheel 53, both of which are controlled by the operating magnet 50. Normally 4that is, while the master switch H is at rest the armature 28 is in locking engagement with the wheel 52; .but when the relay 48 is ener- 'gized this wheel is unlocked at the same time that the energizing circuit for the magnet 50 is closed. The locking mechanism consists of a series of holes near the periphcry of the wheel 52, and a pin on the armature 28 adapted to engage any one of these holes while the magnet 48 is dener ized. When once the circuit is closed throng the operating magnet 50, the gear wheel 53 is rotated automatically, advancing the wiper 46, together -with the wheel 52 and the plungers on the armatures 29 which are in engagement with the shaft and which are also controlled by the gear wheel 53. Vith the preferred arrangement it takes a number of steps-that-is, a number of operations of the magnet 50-to carry the wiper 46 from the contact 45 and onto the next contact 54, and the circuit of the relay 47 is, therefore, broken before the wiper 46 reaches the contact 54. The circuit of the magnet 48 is, of course, in turn also broken before the end of the operation, but the pin 55 on the end of the armature 28 does not. now register with any of the openings 56 near theouter edge of the wheel 52, and for this reason'the circuit of the operating magnet50 is held closed mechanically through the medium of the wheel 52. However, by the time the wiper 46' has advanced to the proper point, in engagement with the contact 54, the pin 55 on the armature 28 has arrived opposite one of the openings 56 and drops thereinto, with the result that the circuit through the magnet 50 is broken and the plunger shaft of the wheel 52, the gear 53 and the wiper 46 are lockedthis, of course, provided the trunk corresponding to the contact 54 is idle. If it is not idle it is obvious that the relay 47 will be reenergized and that the magnet 48 will also be reenergized, thus preventing the pin 55-from falling into any of the openings 56, as explained, until an idle trunk is 'found. By pressing the springs 30 and 31 into contact at the same time the springs 36 and 37 are pressed into contact, the plunger also causes the line relay 57 of the first selector D to energize. This selector is of the general type of selector described and shown in United States Letters Patent No. 815,321, granted March 13, 1906, to Keith, Erickson and Erickson, with the circuits modified for two-wire work. The linerelay 57 of this selector, as stated, energizes as soon as connection is extended thereto from the line. The cur rent in this circuit, it will be seen, flows from ground G through the lower winding of said coil to the side switch wiper 5S, thence to the positive side of the line, through the telephone to the negative side of the line back over the side switch wiper 59, through the upper winding of the relay 5'? to the battery lead 21, thence through battery B to ground G. The line relay 57 upon energizing separates the springs 60 and 61, carrying the latter into engagement with the springs 62. As a result of the closure of conta t between the springs 61 and 62, the sow-acting release relay 63 is energized by a flow of current from ground G through the said springs 61 and 62 and through said relay 63 to the battery lead. The relay (it) upon energizing presses the springs 64 and 65 and the sirings (a; and 67 into contact, taking tie latter -out of engagemern with the spring (38. The closure of contact between the springs (14 and (i5 completes the holding circuit through the bridge cutotl winding --|-l oi the line switch C for preventing the switch (l from falling back as soon as the circuit through the pnll-in winding 2% is broken. This holding circuit, it will be seen, extends from ground G through the springs 5 and iii, conductor 69, bank springs 33 and 32, bridge-cut-ofi' wlnding it of the line switch C to the battery lead 21. The connection having been extended thus far. the subscriber is now in 'lttttillll.\s to operate his dial in accordance with the digits 2- I3--2-U for first operat ing the first selector l) in accordance with the digit :3. next the seeoi'id selector E in accordance with the digit 3 and last. the connector F (Fig. 5) in accordance with the digits 2 and 0. When the subscriber operates his dial -.in accordance with the digit 2 he separates the in'ipulsc springs 4 and 5 at the telephone twice through the medium of the impulse wheel 2. As a result. the relay 57 operates twice, thereby missing the spring (11 to engage the spring (5 twice. Two impulses of current are, therefore, sent through the springs (37 and ('76 to the private magnet relay 70 (which is slow-acting) in series with the vertical magnet 71. thence through the side switch wiper 72 (in first position) to the battery lead 521. At the first impulse the slowacting private magnet relay 70 energizes and remains energized until after the last impulse has been sent. This relay 70 upon energizing closes an energizing clrcuit through the private magnet 73, which private magnet attracts its armature. and re.- mains in readiness to release the side switch to second position after the "ertical magnet 71 has been operated the desired number of til HUS. In this instance the vertical magnet 71 is run-rated twice in accordance with the impulses delivered through this vertical magnet. by the line relay 57. as described. As a result the shaft. 74 and wipers 75, 7t; and 77 are raised to the second level of the. bank contacts. After the last. impulse has been transmitted the slow-acting relay 70 decnergizes and, therefore, the private magnet 73 deiaiergizcs. thereby permitting the side switch to pass to second position.carryim the side switch wipers 51R and 59 and 72 and $8 to second position. As soon as the side switch wiper 72 reaches the second position an energizing circuit. is closed through the rotary magnet 79 from ground (3 through the interruptcr spring of said magnet 79, auxiliary slo '-,acting relay SO seeond-position side switch contact point. side, switch wiper 72 to the battery l-ad 21. By its automatic operation the rotary magnet 79 rotates the shaft and wipers until an idle trunk is found. If the first trunk is idle the shaft and wipers are rotated one step, and a finger on the rotary armature 81 trips the side switch to third position; but if the first trunk is busy the private magnet. 73 is energized, since the side switch wiper 78 is also in second position, and remains energized until the wipers reach an idle trunk line. It is, of course. understood, that when a trunk line is busy the private bank contact (here shown as the contact 82, and which. is in multiple with other private bank contacts of the same group) is connected with the positive battery. It is this positive battery that energizes the private magnet 73 and does not; permit the side switch to trip to third position until after the. .wipers reach an idle trunk. As soon as the side switch trips to third position. in either case, the line relay 57 is disconnected from the line and the tii'('llli from the calling line is ex tended directly through to the second selector switch E by way of the side switch wipers 5S and 59 and the shaft wipers 77 and 75. as indicated by the heavy conductors. It will be seen that the auxiliary relay 80, which energizes in series with the rotary magnet 79. performs two functions: It maintains positive potential on the third-position contact point of the side switch wiper 78 to insure a guarding potential at the private wiper 76 at the instant the side switch passes to third position. without havin to wait for the line relay 83 of the secon selector E to pull up. After the relay 80 has had time to dcencrgize, which. of course. is not. until after the line relay 83 of the second selector I has energized and until guarding potential has been supplied for the private bank contact 82. the release relay (33 of the first selector D is connected through to the conduct'or 84 by way of the third-position contact point Of the side switch wiper 78. whereby the said relay 63 will be n'iaintained energized after the line relay Iii dei nergizes. as a result. of the side switch passing to third position. it will be seen that the second lector E is practically the same as the first selector l), with the exception that there is provided an extra side switch wiper 85 for controlling the ground to the spring 86 instead of connecting the spring 36 direct to ground, as is the corresponding spring 65 in the first selector 1). The object of this arrangeincnt is to cutoff the ground G" at the side switch wiper 85 from the trunk release circuit when the side switch passes from second position. Connection having thus been extended to the second selector; the sul'iscriber o ierates the dial for the digit 3. In so doing he operates the line relav 83 in the. same manner that the. line relay 5? of the selector D was operated. The result is 

